Aircraft and obstacle avoidance method and system thereof

ABSTRACT

An aircraft and an obstacle avoidance method and system thereof. The obstacle avoidance system comprises an image capturing apparatus ( 11 ), a gimbal stability-enhancement system, and a second controller ( 14 ). The gimbal stability-enhancement system comprises a gimbal body ( 12 ) and a gimbal control system ( 13 ). The image capturing apparatus ( 11 ) is arranged on the gimbal body ( 12 ), and is used for capturing an image in a flying direction when the aircraft is flying. The gimbal control system ( 13 ) is connected to the gimbal body ( 12 ). The second controller ( 14 ) is used for determining whether an obstacle exists in the image captured by the image capturing apparatus ( 11 ), and if yes, changing the flying direction of the aircraft according to a position of the obstacle, and if not, controlling the aircraft to fly in the current flying direction.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Chinese Patent ApplicationCN201510369281.2 filed on Jun. 29, 2015, Chinese Patent ApplicationCN201520456110.9 filed on Jun. 29, 2015, Chinese Patent ApplicationCN201510369254.5 filed on Jun. 29, 2015, Chinese Patent ApplicationCN201520459593.8 filed on Jun. 29, 2015, and Chinese Patent ApplicationCN201610282288.5 filed on Apr. 29, 2016. This application refers to allthe disclosure of the above Chinese Patent Applications.

TECHNICAL FIELD

The present invention relates to the field of obstacle avoidance of anaircraft, and particularly to an aircraft and an obstacle avoidancemethod and system thereof.

BACKGROUND

A difficult problem in flying control is how to avoid an obstacle duringthe process of flying for an aircraft. In related arts, it's usuallydependent on an operator's remote control level, that is, the operatorfirst use the naked eye to determine whether an obstacle exists aroundthe aircraft, and then control the aircraft through the remote controlto change the flying direction so as to avoid an obstacle. However, inpractice, the following situations often occur in case of using theabove approach: 1. the operator can't determine whether an obstacleexists around the aircraft if the aircraft has been flying outside theoperator's field of view; 2. the operator may also perform an improperoperation even if the operator see an obstacle, causing the aircraft tocollide with the obstacle.

As can been seen, no matter which situation occurs, the aircraft willinevitably collide with an obstacle, causing the aircraft to be damagedor destroyed.

In addition, the existing aircraft widely uses Global Positioning System(GPS) for navigation, but this navigation method always has somedrawbacks, such as: 1. the GPS signal strength is insufficient toposition. GPS mainly depends on satellites to achieve the positioning.The more the number of satellites is, the more accurate the positioningis. However, some areas are difficult to be covered by a satellite dueto being sheltered by tall buildings or high mountains, which makes theGPS signal strength in these areas is insufficient and thus it isdifficult to position; 2. map data need to be updated constantly,otherwise the accuracy of navigation will be affected. In addition tothe precise positioning of GPS, the existing navigation system also relyon accurate map data to navigate. In order to obtain the latest mapdata, a user often needs to update a software, otherwise a navigationroute error and other issues are likely to appear.

SUMMARY

The technical problem to be solved by the present invention is toovercome the shortcoming of an existing aircraft of incapability ofautomatically avoid an obstacle, and there are provided an aircraft andan obstacle avoidance method and system thereof which can automaticallyavoid an obstacle.

The present invention solves the above technical problem by thefollowing technical solutions.

The present invention provides an obstacle avoidance system of anaircraft. The obstacle avoidance system includes an image capturingapparatus, a gimbal stability-enhancement system, and a secondcontroller; wherein the gimbal stability-enhancement system includes agimbal body and a gimbal control system, the image capturing apparatusis arranged on the gimbal body and is configured for capturing an imagein a flying direction when the aircraft is flying, the gimbal controlsystem is connected to the gimbal body; the second controller isconfigured for determining whether an obstacle exists in the imagecaptured by the image capturing apparatus, and if yes, changing theflying direction of the aircraft according to a position of theobstacle, and if not, controlling the aircraft to fly in the currentflying direction.

The present invention also provides an aircraft, characterized bycomprising an obstacle avoidance system of any combination of the abovedescribed preferred conditions.

The present invention also provides an obstacle avoidance method for anaircraft. The obstacle avoidance method may include: a step S₁ ofcapturing an image in a flying direction when the aircraft is flying; astep S₂ of determining whether an obstacle exists in the captured image,and if yes, performing a step S₃, and if not, performing a step S₄, thestep S₃ of changing the flying direction of the aircraft according to aposition of the obstacle; and the step S₄ of controlling the aircraft tofly in the current flying direction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of one implementation of an obstacleavoidance system of an aircraft according to a first embodiment of thepresent invention.

FIG. 2 is a front view of an aircraft when it is flying forwardaccording to the first embodiment of the present invention.

FIG. 3 is a side view of an aircraft when it is flying forward accordingto the first embodiment of the present invention.

FIG. 4 is a front view of an aircraft when it is flying backwardaccording to the first embodiment of the present invention.

FIG. 5 is a side view of an aircraft when it is flying backwardaccording to the first embodiment of the present invention.

FIG. 6 is a schematic diagram of a flying route of an aircraft and animage captured by an image capturing apparatus according to the firstembodiment of the present invention.

FIG. 7 is a schematic diagram of another flying route according to thefirst embodiment of the present invention.

FIG. 8 is a schematic diagram of yet another flying route according tothe first embodiment of the present invention.

FIG. 9 is a schematic diagram of a further flying route of an aircraftand an image captured by an image capturing apparatus according to thefirst embodiment of the present invention.

FIG. 10 is a front view of an aircraft when it is flying forwardvertically in another implementation according to the first embodimentof the present invention.

FIG. 11 is a side view of an aircraft when it is flying forwardvertically in another implementation according to the first embodimentof the present invention.

FIG. 12 is a front view of an aircraft when it is flying to the rightvertically in another implementation according to the first embodimentof the present invention.

FIG. 13 is a side view of an aircraft when it is flying to the rightvertically in another implementation according to the first embodimentof the present invention.

FIG. 14 is a front view of an aircraft when it is flying to the leftvertically in another implementation according to the first embodimentof the present invention.

FIG. 15 is a side view of an aircraft when it is flying to the leftvertically in another implementation according to the first embodimentof the present invention.

FIG. 16 is a schematic block diagram of a gimbal control system ofanother implementation of an obstacle avoidance system according to afirst embodiment of the present invention.

FIG. 17 is a partial schematic block diagram of another implementationof the obstacle avoidance system according to the first embodiment ofthe present invention.

FIG. 18 is a schematic diagram of a further flying route of an aircraftaccording to the first embodiment of the present invention.

FIG. 19 is a schematic diagram of an image captured by a ground-basedimage capturing apparatus at a position P7 in FIG. 18 and a comparingimage according to the first embodiment of the present invention.

FIG. 20 is a schematic diagram of tracking a vehicle by an aircraft inanother implementation of an obstacle avoidance system according to thefirst embodiment of the present invention.

FIG. 21 is another schematic diagram of tracking a vehicle by anaircraft in another implementation of an obstacle avoidance systemaccording to the first embodiment of the present invention.

FIG. 22 is yet another schematic diagram of tracking a vehicle by anaircraft in another implementation of an obstacle avoidance systemaccording to the first embodiment of the present invention.

FIG. 23 is a flowchart of one implementation of an obstacle avoidancemethod for an aircraft according to a second embodiment of the presentinvention.

FIG. 24 is another flowchart of one implementation of an obstacleavoidance method for an aircraft according to the second embodiment ofthe present invention.

FIG. 25 is a flowchart of another implementation of an obstacleavoidance method for an aircraft according to the second embodiment ofthe present invention.

FIG. 26 is a flowchart of another implementation of an obstacleavoidance method for an aircraft according to the second embodiment ofthe present invention.

DETAILED DESCRIPTION A First Embodiment

As shown in FIG. 1, an obstacle avoidance system according to thepresent embodiment may include an image capturing apparatus 11, a gimbalstability-enhancement system, and a second controller 14. The gimbalstability-enhancement system may include a gimbal body 12 and a gimbalcontrol system 13. The image capturing apparatus 11 may be arranged onthe gimbal body 12 and may be configured for capturing an image in aflying direction when the aircraft is flying. The gimbal control system13 may be connected to the gimbal body 12. FIG. 2 shows a front view ofthe aircraft when it is flying forward. FIG. 3 shows a side view of theaircraft when it is flying forward. FIG. 4 shows a front view of theaircraft when it is flying backward. FIG. 5 shows a side view of theaircraft when it is flying backward.

The gimbal control system 13 may include a first controller, a firstmotor, a second motor and a third motor. The first motor, the secondmotor, and the third motor may be configured for controlling therotation of the gimbal body 12 in three axial directions of athree-dimensional coordinate system respectively. The first controllermay include a balance control module. The balance control module may beelectrically connected to the first motor, the second motor, and thethird motor respectively, and may be configured for controllingoperation of the first motor, the second motor and the third motor toensure that the image capturing direction of the image capturingapparatus 11 is forward.

The first motor, the second motor, and the third motor may be configuredfor controlling the rotation of the gimbal body 12 on the Yaw axis, thePitch axis and the Roll axis, respectively.

The second controller 14 may be configured for determining whether anobstacle exists in the image captured by the image capturing apparatus11, and if yes, changing the flying direction of the aircraft accordingto a position of the obstacle, and if not, controlling the aircraft tofly in the current flying direction. For example, as shown in FIG. 6,the aircraft may originally fly in the direction indicated by the arrowS, and there is an obstacle A at the lower left in front of theaircraft. The circle 11 may represent the flying image capturingapparatus, and the box below the aircraft is an image captured by theimage capturing apparatus. There is an obstacle A in the lower leftcorner of the image, so the flying direction of the aircraft may move upand to the right, changing to fly in the direction indicated by thearrow S′.

In order to enable the obstacle avoidance system to determine a positionof an obstacle more accurately, the obstacle avoidance system mayfurther includes a distance measurement module 15, which is a laserdistance measurement module.

The second controller 14 may be further configured for invoking thedistance measurement module 15 to detect a distance between the aircraftand an obstacle when it is determined that the obstacle exists in animage captured by the image capturing apparatus, changing the flyingdirection of the aircraft according to a position of the obstacle if thedistance is less than or equal to a distance threshold, and controllingthe aircraft to fly in the current flying direction if the distance isgreater than the distance threshold. Taking FIG. 7 as an example, whenthe aircraft is at the position P1, the distance between the obstacle Aand the aircraft measured by the distance measurement module 13 is 10meters. If the preset distance threshold is 5 meters, then the aircraftmay continue to fly along the current flying direction S until theaircraft reaches the position P2, where the distance between theobstacle A and the aircraft measured by the distance measurement module13 is shortened to be 5 meters, and at this point the aircraft maychange the flying direction to fly along the direction indicated by thearrow S′.

In order to avoid frequent adjustments of the flying condition of theaircraft, the second controller 14 may be further configured fordetermining whether the altitude of an obstacle is higher than theflying altitude of the aircraft when it is determined that the obstacleexists in an image captured by the image capturing apparatus 11, and ifyes, increasing the flying altitude of the aircraft, and if not,controlling the aircraft to fly in the current flying direction. As willbe explained with reference to FIG. 8, the aircraft may originally flyin the direction indicated by the arrow S, and there are two obstaclesin front of the aircraft, namely a high mountain B1 and a high mountainB2 respectively. If the aircraft is flying towards the mountain B1, thehigh mountain B1 may exist in an image captured by the image capturingapparatus, and it is determined that the altitude h1 of the highmountain B1 is lower than the flying altitude of the aircraft, then theaircraft will continue to fly in the direction indicated by the arrow S.If the aircraft is flying towards the mountain B2, the high mountain B2may exist in an image captured by the image capturing apparatus, and itis determined that the altitude h2 of the high mountain B2 is higherthan the flying altitude of the aircraft, then the aircraft willincrease the flying altitude, changing to fly in the direction indicatedby the arrow S′.

In another implementation of the obstacle avoidance system of the firstembodiment, the obstacle avoidance system may also adjust the flyingspeed of the aircraft in order to prevent the aircraft from collidingwith an obstacle. Two specific ways to adjust the flying speed areprovided below.

The first way is to adjust the flying speed by detecting a distancebetween the aircraft and the obstacle by means of a distance measurementmodule. The details are as follows.

The second controller 14 may be further configured for invoking thedistance measurement module to detect a distance between the aircraftand the obstacle when it is determined that the obstacle exists in animage captured by the image capturing apparatus 11, and adjusting theflying speed of the aircraft according to a relationship between thedistance and a preset threshold. The adjusting the flying speed of theaircraft according to a relationship between the distance and a presetthreshold may include reducing the flying speed of the aircraft when thedistance is less than or equal to the preset threshold.

Wherein the preset threshold may be set freely, and its specificnumerical size may be considered in conjunction with the distancethreshold. The preset threshold may be smaller than the distancethreshold, in which case when it is determined that an obstacle existsin an image captured by the image capturing apparatus 11, the obstacleavoidance system may first determine whether the distance between theaircraft and the obstacle is less than or equal to the distancethreshold so as to determine whether to change the flying direction, andthen determine whether the distance between the aircraft and theobstacle is less than the preset threshold so as to determine whether toreduce the flying speed. The preset threshold may also be greater thanthe distance threshold, in which case when it is determined that anobstacle exists in an image captured by the image capturing apparatus11, the obstacle avoidance system may first determine whether thedistance between the aircraft and the obstacle is less than the presetthreshold so as to determine whether to reduce the flying speed, andthen determine whether the distance between the aircraft and theobstacle is less than or equal to the distance threshold so as todetermine whether to change the flying direction. The preset thresholdmay also be equal to the distance threshold, in which case when it isdetermined that an obstacle exists in an image captured by the imagecapturing apparatus 11, the obstacle avoidance system may determinewhether the distance between the aircraft and the obstacle is less thanor equal to the distance threshold (which is equal to the presetthreshold) so as to determine whether to change the flying direction andto reduce the flying speed at the same time.

The second way is to adjust the flying speed by means of an imagecaptured by the image capturing apparatus. The details are as follows.

The second controller 14 may be further configured for extracting areference image feature of a reference target from a reference image andextracting a temporary image feature of a temporary target from atemporary image when it is determined that an obstacle exists in animage captured by the image capturing apparatus. The temporary image isan image, among images captured by the image capturing apparatus, wherean obstacle exists and whose capture time is closest to the currenttime, that is, a newly captured image where an obstacle exists. Thereference image is an image, among images captured by the imagecapturing apparatus, where an obstacle exists and whose capture time isprior to the capture time of the temporary image. The obstacle in thereference image may be referred as a reference target, and the obstaclein the temporary image may be referred as a temporary target.

The second controller may be further configured for determining whetherthe reference image feature and the temporary image feature areconsistent, extracting the reference scale information of the referencetarget from the reference image and extracting the temporary scaleinformation of the temporary target from the temporary image when it isdetermined that the reference image feature and the temporary imagefeature are consistent, and adjusting the flying speed of the aircraftaccording to a relationship between the reference scale information andthe temporary scale information. The specific manner of adjusting may becalculating a difference between the reference scale information and thetemporary scale information when the temporary scale information isgreater than the reference scale information, and reducing the flyingspeed of the aircraft if the absolute value of the difference is greaterthan a difference threshold.

The adjusting the flying speed by means of an image captured by theimage capturing apparatus will be described below with reference to FIG.9. As shown in FIG. 9, the aircraft may fly to a position P4 from aposition P3 at the speed V1 in the direction indicated by the arrow S.The image below the position P3 is an image captured by the imagecapturing apparatus at the position P3, which is a reference image, andthe obstacle C in the image is a reference target. The image below theposition P4 is an image captured by the image capturing apparatus at theposition P4, which is a temporary image, and the obstacle C′ in theimage is a temporary target. Whether the obstacle C and the obstacle C′are the same obstacle may be determined by extracting a reference imagefeature of the obstacle C and a temporary image feature of the obstacleC′, and an image feature may be a shape, a color, or the like. Taking animage feature as a shape for an example, it is determined that theobstacle C and the obstacle C′ may be the same obstacle if the shape ofthe obstacle C extracted from the reference image is the same as theshape of the obstacle C′ extracted from the temporary image, and it isdetermined that the obstacle C and the obstacle C′ may be differentobstacles if the shape of the obstacle C extracted from the referenceimage is different from the shape of the obstacle C′ extracted from thetemporary image. Specifically, in FIG. 9, the shape of the obstacle Cand the shape of the obstacle C′ both are triangle, and thus theobstacle C and the shape of the obstacle C′ may be the same obstacle.The reference scale information of the obstacle C′ and the temporaryscale information of the obstacle C may be further extracted, and thescale information may represent the size of the obstacle in the image,such as the side length of the obstacle, the area, and so on. If thetemporary scale information is greater than the reference scaleinformation and a difference between the reference scale information andthe temporary scale information is greater than a difference threshold,then it is indicated that the aircraft may be in a process of graduallyapproaching the obstacle, so the aircraft may be controlled todecelerate, changing to fly at the speed V2 which is less than the speedV1.

In another implementation of the obstacle avoidance system of the firstembodiment, the obstacle avoidance system may include a plurality ofimage capturing apparatuses, which may be arranged in differentdirections of the gimbal body respectively, and may be configured forcapturing images in different directions. The plurality of imagecapturing apparatuses may include the image capturing apparatus forcapturing an image in a flying direction as described above. Theobstacle avoidance system may be provided with a distance measurementmodule for each image capturing apparatus respectively, or all of theimage capturing apparatuses may also share a distance measurement modulewhich is rotatable and capable of measuring a distance in a plurality ofdirections.

Specifically, the obstacle avoidance system may include three imagecapturing apparatuses arranged on the gimbal body respectively, and theoptical axes of the lens of the three image capturing apparatuses arelocated on the same plane and the angle between the optical axes of thelens of two adjacent image capturing apparatuses may be 120°. Further,the obstacle avoidance system may further include an image capturingapparatus arranged on the gimbal body and located below the gimbal bodyand/or an image capturing apparatus arranged on the gimbal body andlocated above the gimbal body.

The second controller may be further configured for splicing the imagescaptured by these image capturing apparatuses into a panoramic image.The obstacle avoidance system can observe the circumstances around theaircraft in all directions through the panoramic image.

In addition, the obstacle avoidance system may further include awireless sending module 16. The wireless sending module 16 may beconfigured for transmitting an image captured by the image capturingapparatus 11 to a remote controller for controlling the aircraft. Theremote controller may display the received image so that an operator cansee if there is an obstacle in front of the aircraft.

The second controller 14 may be further configured for receiving acontrol signal from the remote controller and controlling the aircraftaccording to the control signal.

In another implementation of the obstacle avoidance system of the firstembodiment, as shown in FIGS. 10-15, the obstacle avoidance system mayfurther include a ground-based image capturing apparatus 26, which maybe arranged on the gimbal body, and the image capturing direction of theground-based image capturing apparatus 26 may be vertically downward.FIG. 10 shows a front view of an aircraft when it is flying forwardvertically. FIG. 11 shows a side view of an aircraft when it is flyingforward vertically. Fig. FIG. 12 shows a front view of an aircraft whenit is flying to the right vertically. FIG. 13 shows a side view of anaircraft when it is flying to the right vertically. FIG. 14 shows afront view of an aircraft when it is flying to the left vertically. FIG.15 shows a side view of an aircraft when it is flying to the leftvertically.

As shown in FIG. 16, the gimbal control system may further comprise athird controller 21, a fourth motor 22, a fifth motor 23, and a sixthmotor 24. The fourth motor 22, the fifth motor 23, and the sixth motor24 may be configured for controlling the rotation of the gimbal body inthree axial directions of a three-dimensional coordinate systemrespectively. The third controller 21 may include a first balancecontrol module 211. The first balance control module 211 may beelectrically connected to the fourth motor 22, the fifth motor 23, andthe sixth motor 24 respectively, and may be configured for controllingoperations of the fourth motor 22, the fifth motor 23, and the sixthmotor 24 to ensure that the image capturing direction of theground-based image capturing apparatus 26 is vertically downward.

The fourth motor 22, the fifth motor 23, and the sixth motor 24 may beconfigured for controlling the rotation of the gimbal body on the Yawaxis, the Pitch axis and the Roll axis, respectively. The fourth motor22 and the first motor may be the same motor or different motors, andthe fifth motor 23 and the second motor may be the same motor ordifferent motors, and the sixth motor 24 and the third motor may be thesame motor or different motors.

As shown in FIG. 17, the obstacle avoidance system of the presentembodiment may further include a fourth controller 25.

The ground-based image capturing apparatus 26 may be configured forcapturing an image when the aircraft is flying. In capturing by theground-based image capturing apparatus 26, a time interval for capturingan image may be preset. For example, the time interval may be set as 1minute, that is, the ground-based image capturing apparatus 26 maycapture an image once every 1 minute while the aircraft is flying. Thecaptured images may directly show the terrain, buildings or the likeunder the aircraft.

The fourth controller 25 may include an acquisition module 251 and acorrection module 252.

The acquisition module 251 may be configured for acquiring a set ofreference images for displaying a designated flying route. The referenceimages may be topographic maps of the designated flying route. Thedesignated flying route may include a return route for the aircraft, anda topographic map of the return route may be captured by theground-based image capturing apparatus 26 when the aircraft is on theoutward voyage. Taking FIG. 18 as an example, a route for the aircrafton the outward voyage may be from a position P5 to a position P6, and aset of topographic maps D1, D2, . . . , Dn may be captured by theground-based image capturing apparatus on the outward voyage (may becaptured once every the time interval, and n is a positive integer, thespecific contents of the topographic maps are not shown), thetopographic maps D1, D2, . . . , Dn may be used as reference imagesduring the return voyage of the aircraft flying from the position P6back to the position P5. The designated flying route may further includeany route that specifies a starting point and an ending point, and forsuch designated flying route, the obstacle avoidance system may obtain acorresponding reference image by pre-storing or downloading via thenetwork.

The correction module 252 may be configured for comparing a newlycaptured image with the set of reference images when the aircraft isflying, and correcting the current flying route of the aircraft.

In particular, the correction module 252 may include an image processingmodule 2521, a comparison module 2522, and a flying control module 2523.

The image processing module 2521 may be configured for selecting areference image from the set of reference images as a comparing image,and extracting the feature information from a newly captured image andthe comparing image respectively. More specifically, the imageprocessing module 2521 may extract the feature information of each ofthe set of reference images and select a reference image having thelargest amount of same feature information as the newly captured imageas the comparing image. Also taking FIG. 18 as an example, during thereturn voyage of the aircraft flying from the position P6 back to theposition P5, the image D′ may be captured at a position P7 (P7 isbetween P6 and P5), and an image having the largest amount of samefeature information as the image D′ (i.e., an image closest to the imageD′) may be selected from the topographic maps D1-Dn as a comparingimage.

The comparison module 2522 may be configured for comparing the offset ofthe same feature information in the newly captured image and thecomparing image.

The flying control module 2523 may be configured for changing thecurrent flying direction and flying altitude of the aircraft accordingto the offset.

For example, if the position of the same feature information in thenewly captured image is shifted to the right relative to its position inthe comparing image, the flying direction of the aircraft should bemoved to the left. The calculation of the offset may also beappropriately combined with the current flying altitude and/or flyingspeed of the aircraft, and the like. Further explanation will be madebelow in connection with FIG. 19, an image D′ may be captured by theground-based image capturing apparatus when the aircraft arrives at theposition P7 in FIG. 18, wherein there is a lake E in the image D′. Thetopographic map Dm (1≤M≤N) may be one of the reference images and havethe largest amount of same feature information (including the lake E) asthe image D′, and thus the topographic map Dm may be used as thecomparing image, wherein the lake E is the same feature information. Bycomparing the image D′ and the topographic map Dm, it can be known thatthe position of the lake E in the image D′ is shifted to the rightrelative to the position of the lake E in the topographic map Dm, thenthe flying direction of the aircraft should be moved to the left on thebasis of the original flying direction to reduce the offset d of thelake E in the image D′ and the topographic map Dm.

The second controller may further be configured for splicing the imagescaptured by the image capturing apparatus and the images captured by theground-based image capturing apparatus into a panoramic image.

The obstacle avoidance system of the present embodiment may correct theflying route continuously by repeatedly capturing images below theaircraft and comparing the images with the reference images, so as torealize the addressing and return of the aircraft quickly andaccurately.

In another implementation of the obstacle avoidance system of the firstembodiment, the obstacle avoidance system may also be suitable fortarget tracking of the aircraft, and a target tracking method suitablefor the aircraft may be applied to the tracking aircraft. The followingaircraft body may be part of the aircraft.

Since a GPS signal receiver may be arranged on a target to be tracked,the GPS signal receiver may acquire the latitude and longitudecoordinates returned from a GPS system and may forward them. If theaircraft body is initiated, it may acquire the latitude and longitudecoordinates forwarded by the GPS signal receiver. The aircraft body mayfly toward a location corresponding to the GPS positioning signalaccording to the latitude and longitude coordinates, and during theflight, the image capturing apparatus may take pictures of an area wherea reference target is located to obtain a reference image.

The image capturing apparatus may extract from a reference image areference image feature of a reference target and the initial positioninformation of the reference target in the reference image, and thereference target may be at a position of a certain point of thereference image. In practice, the coordinate values of the point in thecoordinate system established based on the reference image may bedenoted as the initial position information. Similarly, the temporaryposition information described hereinafter may be a certain point of atemporary target in a temporary image, and in practice, the coordinatevalues of the point in the coordinate system established based on thetemporary image may be denoted as the temporary position information. Inaddition, the reference image feature and the initial positioninformation may be initialized in the aircraft body. The reference imagefeature may be used as a reference feature for subsequent selection of atarget to be tracked, and a target consistent with the reference featuremay be recorded as a target to be tracked. The initial positioninformation may be used as a reference point of a target to be trackedin an image captured by the image capturing apparatus. The coordinatesystem of the reference image is the same as that of the temporaryimage, and in the present invention, the vertex at the upper left cornerof the reference image is the coordinate origin. The part on the rightof the coordinate origin is the positive axis of the x-axis, and thepart below the coordinate origin is the positive axis of the y-axis, andthe size of the coordinates may be calculated in a pixel as the smallestunit. When a target to be tracked deviates from the reference point, theaircraft body may be controlled to rotate to achieve the transformationof the image capturing angle of the image capturing apparatus and tocause the target to be tracked to return to the position of thereference point again. In practice, the background subtractiontechnology and the like may be used to extract the gray, color and otherinformation of the reference target, the interference caused by thenoise, pseudo-target and the like may be eliminated through thethreshold processing, morphological operation and other techniques, andthen the reference image feature and the initial position information ofthe reference target may be obtained through the contour extractiontechnology and the like.

Since the image capturing apparatus takes pictures in real time duringthe flight, a temporary image feature of a temporary target and thetemporary position information of the temporary target in the temporaryimage may be extracted from the temporary image when the image capturingapparatus acquires the temporary image showing the temporary target. Atemporary image feature may include, but not limited to, the gray,color, shape or the like of a temporary target. In practice, a temporaryimage feature of a temporary target may be extracted selectivelyaccording to the usage scenario.

If the reference image feature and the temporary image feature areconsistent (for example, it is assumed that the color and shapeinformation of the reference target may be extracted in the referenceimage, and the color and shape information of the temporary target maybe extracted in the temporary image, and only if the color of thetemporary target is consistent with the color of the reference target,and the shape of the temporary target is consistent with the shape ofthe reference target), it is determined that the temporary target is thetarget to be tracked. The image capturing apparatus may calculate thedeviation direction based on the difference between the initial positioninformation and the temporary position information, that is, maycalculate the difference between a horizontal coordinate of the initialposition information (i.e., the abscissa of the initial positioninformation) and a horizontal coordinate of the temporary positioninformation (i.e., the abscissa of the temporary position information)and the difference between a vertical coordinate of the initial positioninformation (i.e., the ordinate of the initial position information) anda vertical coordinate of the temporary position information (i.e., theordinate of the temporary position information), and determine thedeviation direction based on the two differences. The aircraft body maycontinue to track the temporary target based on the deviation directionso that the difference between the initial position information and thetemporary position information may reduce gradually. For example, if thetemporary position information deviates a certain distance to the rightrelative to the initial position information, the aircraft body may flytoward to the right side so that the temporary position information maygradually approach to the initial position information. The temporaryimage feature of an target may include but not limited to gradientdirection histogram, local binary pattern histogram, scale invariantfeature transformation and accelerated robust feature, that is, atemplate matching method, a histogram matching method or a FLANN-basedmatching method may be used to lock a temporary target to be the targetto be tracked.

The aircraft body may track based on the deviation direction.

In addition, since targets to be tracked by the aircraft body mayinclude static targets and dynamic targets, it is necessary for theaircraft body to keep a reasonable distance from a target in order toavoid collision of the aircraft body with the target while avoidinglosing track of the target. When the aircraft body is too close to atemporary target, the scale of the target in an image captured by theimage capturing apparatus may become larger, and when the aircraft bodyis too far from a temporary target, the scale of the target in an imagecaptured by the image capturing apparatus may become smaller. Bycontrolling the aircraft body to increase or reduce its flying speed,the distance between the aircraft body and a temporary target mayconform to the following constraint: 0.9*Z<X<1.1*Z, where Z may be apreset threshold, and X may be the distance between the aircraft bodyand a temporary target. For example, a vehicle is moving forward at aconstant speed, and an aircraft may be responsible for tracking thevehicle and may keep a distance of 500 meters from the vehicle, wherein500 meters is a preset threshold.

The aircraft body may determine the distance from the vehicle accordingto a change in a width value and a height value of a temporary target ina temporary image, wherein the width value may refer to a horizontallength value of the temporary target in the temporary image, and theheight value may refer to a longitudinal length value of the temporarytarget in the temporary image. In the present embodiment, the imagecapturing apparatus may extract the first reference scale informationand the second reference scale information of the reference target fromthe reference image, wherein the first reference scale information maybe a width value of the reference target in the reference image, and thesecond reference scale information may be a height value of thereference target in the reference image.

When the image capturing apparatus determines that the reference imagefeature is consistent with the temporary image feature, the imagecapturing apparatus may extract the first temporary scale informationand the second temporary scale information of the temporary target fromthe temporary image, wherein the first temporary scale information maybe a width value of the temporary target in the temporary image, and thesecond temporary scale information may be a height value of thetemporary target in the temporary image.

When the value of the first reference scale information is larger thanthe value of the first temporary scale information, the image capturingapparatus may calculate a difference between the first reference scaleinformation and the first temporary scale information, and if theabsolute value of the difference is larger than a preset threshold, theaircraft body may increase its flying speed.

When the value of the first reference scale information is smaller thanthe value of the first temporary scale information, the image capturingapparatus may calculate a difference between the first reference scaleinformation and the first temporary scale information, and if theabsolute value of the difference is larger than a preset threshold, theaircraft body may reduce its flying speed.

When the value of the second reference scale information is larger thanthe value of the second temporary scale information, the image capturingapparatus may calculate a difference between the second reference scaleinformation and the second temporary scale information, and if theabsolute value of the difference is larger than a preset threshold, theaircraft body may increase its flying speed.

When the value of the second reference scale information is smaller thanthe value of the second temporary scale information, the image capturingapparatus may calculate a difference between the second reference scaleinformation and the second temporary scale information, and if theabsolute value of the difference is larger than a preset threshold, theaircraft body may reduce its flying speed.

When a position of the temporary target captured by the image capturingapparatus in the temporary image is located away from the referencepoint, it is necessary to adjust the flying direction of the aircraftbody in time. The position of the temporary target in the temporaryimage may always be kept at the reference point by the adjustment of theflying direction. Therefore the target tracking method suitable for theaircraft may also include the following steps.

When the image capturing apparatus determines that a temporary verticalcoordinate of the temporary position information (i.e., the temporaryordinate of the temporary position information) is not consistent withan initial vertical coordinate of the initial position information(i.e., the initial ordinate of the initial position information), adifference between the temporary vertical coordinate and the initialvertical coordinate may be calculated to generate longitudinaldisplacement information, wherein the initial vertical coordinate may bea position coordinate acquired by the image capturing apparatus in thecoordinate system established based on the reference image, and thetemporary vertical coordinate may be a position coordinate acquired bythe image capturing apparatus in the coordinate system established basedon the temporary image.

The pitch axis of the gimbal may be rotated according to thelongitudinal displacement information to adjust a vertical angle of theimage capturing apparatus for capturing a temporary image.

When a temporary horizontal coordinate of the temporary positioninformation is not consistent with an initial horizontal coordinate ofthe initial position information, a difference between the temporaryhorizontal coordinate and the initial horizontal coordinate may becalculated to generate lateral displacement information, wherein theinitial horizontal coordinate may be a position coordinate acquired bythe image capturing apparatus in the coordinate system established basedon the reference image, the temporary horizontal coordinate may be aposition coordinate acquired by the image capturing apparatus in thecoordinate system established based on the temporary image.

The yaw axis of the gimbal may be rotated according to the lateraldisplacement information to adjust a horizontal angle of the imagecapturing apparatus for capturing a temporary image.

In another implementation, the pitch axis and yaw axis of the gimbal maybe rotated simultaneously so that the temporary vertical coordinate andthe temporary horizontal coordinate may change simultaneously.

Further, in the process of tracking a temporary target by the aircraftbody, the temporary target may be subject to deformation, a color changeor the like due to its own reasons or external reasons. The temporaryimage features of the target including but not limited to gradientdirection histogram, local binary pattern histogram, scale invariantfeature transformation, and accelerated robust feature may change. Inthis case, the present invention employs a method of establishing atarget group and updating a temporary image feature, or the like.

The image capturing apparatus may search for a similar target in realtime in a temporary image and extract a reference feature of a similartarget. When the reference feature is consistent with one of thetemporary image features, for example, the color of the similar targetis the same as the color of the temporary target, or the color and shapeof the similar target are the same as the color and shape of thetemporary target respectively, the similar target then may be regardedas a candidate target in the target group.

When the aircraft body detects a change in any of the temporary imagefeature, the temporary position information, the first temporary scaleinformation, and the second temporary scale information, the temporaryimage feature, the temporary position information, the first temporaryscale information, and the second temporary scale information after thechange may be used to update the temporary image feature, the temporarylocation information, the first temporary scale information, and thesecond temporary scale information before the change respectively, toeliminate or reduce the interference with the tracking system due tofactors such as a target appearance change or occlusion and so on, andthus to improve the stability of the tracking system and the accuracy ofthe tracking results.

In order to facilitate an operator to view, in the present invention,the position information and the scale information of the candidatetarget or the temporary target tracked by the aircraft body may beselectively displayed on the image capturing apparatus (the imagecapturing apparatus may have a display function). In one embodiment, theimage capturing apparatus may be connected to a display, and the displaymay be used to display the position information and the scaleinformation of the candidate target or the temporary target.

The image capturing apparatus may acquire and calculate the provisionalcoordinate information, the first provisional scale information and thesecond provisional scale information of the similar target, wherein thefirst provisional scale information may be a width value of the similartarget in the temporary image, and the second provisional scaleinformation may be a height value of the similar target in the temporaryimage.

When the image capturing apparatus detects a target group and the imagecapturing apparatus tracks a temporary target, the provisionalcoordinate information, the first provisional scale information, and thesecond provisional scale information of the target group may be weightedwith the temporary position information, the first temporary scaleinformation and second temporary scale information of the temporarytarget respectively, and the result of the weighting calculation may beoutput to the image capturing apparatus to display the result of theweighting calculation.

As an example of tracking a vehicle by the aircraft, as shown in FIG.20, the image capturing direction of the image capturing apparatus ofthe aircraft may be the direction of the arrow F1, which is toward avehicle to be tracked. When there is more than one vehicle in front ofthe aircraft and the colors of the vehicles are the same (are all red),the vehicles other than a temporary target may be classified into atarget group. In this case, the provisional coordinate information, thefirst provisional scale information, and the second provisional scaleinformation of each vehicle in the target group may be weighted with thetemporary position information, the first temporary scale informationand the second temporary scale information of the temporary target,namely the vehicle to be tracked, respectively, and the result of theweighting calculation may be output to the image capturing apparatus todisplay the result of the weighting calculation.

When the image capturing apparatus does not detect a target group andthe image capturing apparatus tracks a temporary target, the temporaryposition information, the first temporary scale information, and thesecond temporary scale information of the temporary target may be outputto the image capturing apparatus to display the temporary positioninformation, the first temporary scale information and the secondtemporary scale information.

As an example of tracking a vehicle by the aircraft, as shown in FIG.21, the image capturing direction of the image capturing apparatus ofthe aircraft may be the direction of the arrow F2, which is toward avehicle to be tracked. When there is only one vehicle in front of theaircraft, the vehicle is a temporary target. The temporary positioninformation, the first temporary scale information, and the secondtemporary scale information of the vehicle may be output to the imagecapturing apparatus to display the temporary position information, thefirst temporary scale information, and the second temporary scaleinformation.

When the image capturing apparatus detects a target group and the imagecapturing apparatus does not track a temporary target, the provisionalcoordinate information, the first provisional scale information, and thesecond provisional scale information of the target group may be weightedrespectively, and the result of the weighting calculation may be outputto the image capturing apparatus to display the result of the weightingcalculation.

As an example of tracking a vehicle by the aircraft, as shown in FIG.22, the image capturing direction of the image capturing apparatus ofthe aircraft may be the direction of the arrow F3, which is toward avehicle to be tracked. When there are a plurality of vehicles in frontof the aircraft but none of them is a temporary target, and one of thefeatures of the vehicles is the same as that of the vehicle to betracked (the colors are all red), the plurality of vehicles may beclassified into a target group. In this case, the provisional coordinateinformation, the first provisional scale information, and the secondprovisional scale information of each vehicle in the target group may beweighted respectively, and the result of the weighting calculation maybe output to the image capturing apparatus to display the result of theweighting calculation. When the image capturing apparatus does notdetect a target group and the image capturing apparatus does not track atemporary target, no information will be output to the image capturingapparatus.

The above results output to the image capturing apparatus may also bedisplayed on the display so that an operator can view the details oftracking a target by the aircraft in real time.

For example, the aircraft body may track a bird. The bird to be trackedmay receive a GPS signal. If the aircraft body is initiated, theaircraft body may fly toward a location corresponding to the GPSpositioning signal, and during the flight, the image capturing apparatusmay take pictures of an area where the bird is located to obtain areference image. The image capturing apparatus may extract a referenceimage feature of a reference target from the reference image, forexample, the size and the color of the bird, and the like, and mayextract the initial position information of the reference target in thereference image. It is assumed that the bird is located at the centerpoint of the reference image. The aircraft body may take pictures duringthe flight. When the image capturing apparatus acquires a temporaryimage showing a temporary target, a temporary image feature of thetemporary target and the temporary position information of the temporarytarget in the temporary image may be extracted from the temporary image.When the reference image feature and the temporary image feature areconsistent, the image capturing apparatus may calculate the deviationdirection based on the difference between the initial positioninformation and the temporary position information. The aircraft bodymay track based on the deviation direction. In addition, the imagecapturing apparatus may extract a width value and a height value of thereference target from the reference image. When the image capturingapparatus determines that the reference image feature and the temporaryimage feature are consistent, that is, the temporary target is the birdto be tracked, the image capturing apparatus may extract a width valueand a height value of the bird from the temporary image. When the widthvalue and the height value of the reference target are inconsistent withthe width value and the height value of the bird extracted in thetemporary image, it may show that the distance between the aircraft bodyand the bird may deviate from a preset threshold. For example, if thewidth value of the reference target is greater than the width value ofthe bird extracted from the temporary image, it may show that thedistance between the aircraft body and the bird may be larger than athreshold, therefore the aircraft body may increase its flying speed sothat the distance between the aircraft body and the temporary target maybe kept within a threshold range. The threshold range may be set between0.9*threshold and 1.1*threshold in the present invention. When thetemporary target deviates from the center point of the reference image,the image capturing apparatus may calculate a difference between atemporary vertical coordinate and an initial vertical coordinate andgenerate longitudinal displacement information, and the pitch axis ofthe aircraft body may be rotated according to the longitudinaldisplacement information to adjust a vertical angle of the imagecapturing apparatus for capturing a temporary image. Thereafter, theimage capturing apparatus may calculate a difference between a temporaryhorizontal coordinate and an initial horizontal coordinate and generatelateral displacement information, and the yaw axis of the aircraft bodymay be rotated according to the lateral displacement information toadjust a horizontal angle of the image capturing apparatus for capturinga temporary image. In this way, by adjusting the aircraft body, theflying direction of the aircraft body may direct toward the bird to betracked in real time, while in the temporary image acquired by the imagecapturing apparatus, the bird may be kept at the center point of thereference image, and thus it is convenient for viewing, while avoidinglosing track of the target.

The technical effects of the obstacle avoidance system provided by thepresent embodiment is that during the flight of the aircraft body towarda location corresponding to the GPS positioning signal, the imagecapturing apparatus may acquire a reference image and a temporary image,and obtain feature parameters from the reference image and the temporaryimage, so that the aircraft body may track a target by matching andcalculating of the feature parameters without tracking by relying on theGPS positioning signal, thus improving the accuracy of the tracking.

The aircraft of the first embodiment may include the obstacle avoidancesystem of any of the implementations of the first embodiment and othercomponents of the existing aircraft. The obstacle avoidance system maybe arranged on the aircraft body and its specific position is not shownin the figures.

A Second Embodiment

As shown in FIG. 23, an obstacle avoidance method for an aircraft mayinclude the following steps.

In step 31, an image in a flying direction may be captured when theaircraft is flying.

In step 32, whether an obstacle exists in the captured image may bedetermined, and if yes, then step 33 may be performed, and if not, thenstep 34 may be performed.

In step 33, the flying direction of the aircraft may be changedaccording to a position of the obstacle.

In step 34, the aircraft may be controlled to fly in the current flyingdirection.

In order to avoid frequent adjustments of the flying condition of theaircraft and to enable the obstacle avoidance system to determine aposition of an obstacle more accurately, as shown in FIG. 24, theobstacle avoidance method may further include performing the followingstep 35 when it is determined that an obstacle exists in the capturedimage: determining whether the altitude of the obstacle is higher thanthe flying altitude of the aircraft, and if yes, performing step 36, andif not, performing step 34.

In step 36, a distance between the aircraft and the obstacle may bedetected, and the flying altitude of the aircraft may be increased ifthe distance is less than or equal to a distance threshold, and step 34may be performed if the distance is greater than the distance threshold.

In addition, the obstacle avoidance method may further include thefollowing steps: transmitting the captured image to a remote controllerfor controlling the aircraft, receiving a control signal from the remotecontroller and controlling the aircraft according to the control signal.

By using the obstacle avoidance method, an operator may determine froman image in front of the aircraft which is displayed from the remotecontroller whether it is necessary to avoid the obstacle. And ifnecessary, the operator may further manually control the aircraftthrough the remote controller to adjust so as to pass through the frontarea safely.

In another implementation of the second embodiment of the presentinvention, the obstacle avoidance method may also be used to adjust theflying speed of the aircraft in order to prevent the aircraft fromcolliding with an obstacle. Two specific ways to adjust the flying speedare provided below.

The first way is to adjust the flying speed by detecting a distancebetween the aircraft and the obstacle by means of a distance measurementmodule. It may include the following specific steps: detecting adistance between the aircraft and an obstacle when it is determined thatthe obstacle exists in the captured image in step 32, and adjusting theflying speed of the aircraft according to a relationship between thedistance and a preset threshold. The adjusting the flying speed of theaircraft according to a relationship between the distance and a presetthreshold may include reducing the flying speed of the aircraft when thedistance is less than or equal to the preset threshold. Wherein thepreset threshold may be set freely, and its specific numerical size maybe considered in conjunction with the distance threshold.

The second way is to adjust the flying speed by means of an imagecaptured by the image capturing apparatus. It may include the followingspecific steps: extracting a reference image feature of a referencetarget from a reference image and extracting a temporary image featureof a temporary target from a temporary image when it is determined thatthe obstacle exists in the captured image in step 32. The temporaryimage is an image, among the captured images, where an obstacle existsand whose capture time is closest to the current time, that is, a newlycaptured image where an obstacle exists. The reference image is animage, among the captured images, where an obstacle exists and whosecapture time is prior to the capture time of the temporary image. Theobstacle in the reference image may be referred as a reference target,and the obstacle in the temporary image may be referred as a temporarytarget.

It may further include the following specific steps: determining whetherthe reference image feature and the temporary image feature areconsistent, extracting the reference scale information of the referencetarget from the reference image and extracting the temporary scaleinformation of the temporary target from the temporary image when it isdetermined that the reference image feature and the temporary imagefeature are consistent, and adjusting the flying speed of the aircraftaccording to a relationship between the reference scale information andthe temporary scale information. The specific manner of adjusting may becalculating a difference between the reference scale information and thetemporary scale information when the temporary scale information isgreater than the reference scale information, and reducing the flyingspeed of the aircraft if the absolute value of the difference is greaterthan a difference threshold.

In another implementation of the obstacle avoidance method of the secondembodiment, the aircraft may include a plurality of image capturingapparatuses, which may be arranged in different directions of the gimbalbody respectively, and may be configured for capturing images indifferent directions. One of the plurality of image capturingapparatuses may be configured for capturing an image in a flyingdirection when the aircraft is flying.

The obstacle avoidance method may further include: splicing the imagescaptured by these image capturing apparatuses into a panoramic image.The obstacle avoidance system can observe the circumstances around theaircraft in all directions through the panoramic image.

In another implementation of the obstacle avoidance method of the secondembodiment, the aircraft may further include a ground-based imagecapturing apparatus, which may be arranged on the gimbal body, and theimage capturing direction of the ground-based image capturing apparatusmay be vertically downward. The ground-based image capturing apparatusmay be configured for capturing an image when the aircraft is flying. Asshown in FIG. 24, the obstacle avoidance method may further include thefollowing steps.

In step 41, a set of reference images for displaying a designated flyingroute may be acquired. The reference images may be topographic maps ofthe designated flying route. The designated flying route may include areturn route for the aircraft, and a topographic map of the return routemay be captured by the ground-based image capturing apparatus when theaircraft is on the outward voyage. The designated flying route mayfurther include any route that specifies a starting point and an endingpoint, and for such designated flying route, the obstacle avoidancemethod may obtain a corresponding reference image by pre-storing ordownloading via the network.

In step 42, a newly captured image may be compared with the set ofreference images when the aircraft is flying, and the current flyingroute of the aircraft may be corrected. The step 42 may include thefollowing steps.

In step 421, a reference image may be selected from the set of referenceimages as a comparing image, and the feature information may beextracted from a newly captured image and the comparing imagerespectively. More specifically, the feature information of each of theset of reference images may be extracted and a reference image havingthe largest amount of same feature information as the newly capturedimage may be selected as the comparing image.

In step 422, the offset of the same feature information in the newlycaptured image and the comparing image may be compared.

In step 423, the current flying direction and flying altitude of theaircraft may be changed according to the offset.

Further, the aircraft may include a plurality of image capturingapparatuses, which may be arranged in different directions of the gimbalbody of the aircraft respectively, and may be configured for capturingimages in different directions respectively. The capturing images indifferent directions may include capturing an image in a flyingdirection when the aircraft is flying. The obstacle avoidance method mayfurther include: splicing the images captured by these image capturingapparatuses and the images captured by the ground-based image capturingapparatus into a panoramic image.

The obstacle avoidance method of the present embodiment may realize theaddressing and return of the aircraft quickly and accurately byrepeatedly capturing images below the aircraft and comparing the imageswith the reference images to correct the flying route continuously.

In another implementation of the obstacle avoidance method of the secondembodiment, an obstacle avoidance method suitable for target tracking ofthe aircraft may be provided, and a target tracking method suitable forthe aircraft may be applied to the tracking aircraft. As shown in FIG.26, the obstacle avoidance method may include the following steps.

In step 51, since a GPS signal receiver may be arranged on a target tobe tracked, the GPS signal receiver may acquire the latitude andlongitude coordinates returned from a GPS system and may forward them.If the aircraft body is initiated, it may acquire the latitude andlongitude coordinates forwarded by the GPS signal receiver. The aircraftbody may fly toward a location corresponding to the GPS positioningsignal according to the latitude and longitude coordinates, and duringthe flight, the image capturing apparatus may take pictures of an areawhere a reference target is located to obtain a reference image.

In step 52, the image capturing apparatus may extract from the referenceimage a reference image feature of the reference target and the initialposition information of the reference target in the reference image, andthe reference target may be at a position of a certain point of thereference image. In practice, the coordinate values of the point in thecoordinate system established based on the reference image may bedenoted as the initial position information. Similarly, the temporaryposition information described hereinafter may be a certain point of atemporary target in a temporary image, and in practice, the coordinatevalues of the point in the coordinate system established based on thetemporary image may be denoted as the temporary position information. Inaddition, the reference image feature and the initial positioninformation may be initialized in the aircraft body. The reference imagefeature may be used as a reference feature for subsequent selection of atarget to be tracked, and a target consistent with the reference featuremay be recorded as a target to be tracked. The initial positioninformation may be used as a reference point of a target to be trackedin an image captured by the image capturing apparatus. The coordinatesystem of the reference image is the same as that of the temporaryimage, and in the present invention, the vertex at the upper left cornerof the reference image is the coordinate origin. The part on the rightof the coordinate origin is the positive axis of the x-axis, and thepart below the coordinate origin is the positive axis of the y-axis, andthe size of the coordinates may be calculated in a pixel as the smallestunit. When a target to be tracked deviates from the reference point, theaircraft body may be controlled to rotate to achieve the transformationof the image capturing angle of the image capturing apparatus and tocause the target to be tracked to return to the position of thereference point again. In practice, the background subtractiontechnology and the like may be used to extract the gray, color and otherinformation of the reference target, the interference caused by thenoise, pseudo-target and the like may be eliminated through thethreshold processing, morphological operation and other techniques, andthen the reference image feature and the initial position information ofthe reference target may be obtained through the contour extractiontechnology and the like.

In step 53, since the image capturing apparatus takes pictures in realtime during the flight, a temporary image feature of the temporarytarget and the temporary position information of the temporary target inthe temporary image may be extracted from the temporary image when theimage capturing apparatus acquires the temporary image showing thetemporary target. Temporary image features may include, but not limitedto, the gray, color, shape or the like of the temporary target. Inpractice, a temporary image feature of a temporary target may beextracted selectively according to the usage scenario.

In step 54, if the reference image feature and the temporary imagefeature are consistent (for example, it is assumed that the color andshape information of the reference target may be extracted in thereference image, and the color and shape information of the temporarytarget may be extracted in the temporary image, and only if the color ofthe temporary target is consistent with the color of the referencetarget, and the shape of the temporary target is consistent with theshape of the reference target), it is determined that the temporarytarget is the target to be tracked. The image capturing apparatus maycalculate the deviation direction based on the difference between theinitial position information and the temporary position information,that is, may calculate the difference between a horizontal coordinate ofthe initial position information (i.e., the abscissa of the initialposition information) and a horizontal coordinate of the temporaryposition information (i.e., the abscissa of the temporary positioninformation) and the difference between a vertical coordinate of theinitial position information (i.e., the ordinate of the initial positioninformation) and a vertical coordinate of the temporary positioninformation (i.e., the ordinate of the temporary position information),and determine the deviation direction based on the two differences. Theaircraft body may continue to track the temporary target based on thedeviation direction so that the difference between the initial positioninformation and the temporary position information may reduce gradually.For example, if the temporary position information deviates a certaindistance to the right relative to the initial position information, theaircraft body may fly toward to the right side so that the temporaryposition information may gradually approach to the initial positioninformation. The temporary image features of an target may include butnot limited to gradient direction histogram, local binary patternhistogram, scale invariant feature transformation and accelerated robustfeature, that is, a template matching method, a histogram matchingmethod or a FLANN-based matching method may be used to lock a temporarytarget to be the target to be tracked.

In step 55, the aircraft body may track based on the deviationdirection.

In addition, since targets to be tracked by the aircraft body mayinclude static targets and dynamic targets, it is necessary for theaircraft body to keep a reasonable distance from a target in order toavoid collision of the aircraft body with the target while avoidinglosing track of the target. When the aircraft body is too close to atemporary target, the scale of the target in an image captured by theimage capturing apparatus may become larger, and when the aircraft bodyis too far from a temporary target, the scale of the target in an imagecaptured by the image capturing apparatus may become smaller. Bycontrolling the aircraft body to increase or reduce its flying speed,the distance between the aircraft body and a temporary target mayconform to the following constraint: 0.9*Z<X<1.1*Z, where Z may be apreset threshold, and X may be the distance between the aircraft bodyand a temporary target. For example, a vehicle is moving forward at aconstant speed, and an aircraft may be responsible for tracking thevehicle and may keep a distance of 500 meters from the vehicle, wherein500 meters is a preset threshold.

The aircraft body may determine the distance from the vehicle accordingto a change in a width value and a height value of a temporary target ina temporary image, wherein the width value may refer to a horizontallength value of the temporary target in the temporary image, and theheight value may refer to a longitudinal length value of the temporarytarget in the temporary image. In the present embodiment, the imagecapturing apparatus may extract the first reference scale informationand the second reference scale information of the reference target fromthe reference image, wherein the first reference scale information maybe a width value of the reference target in the reference image, and thesecond reference scale information may be a height value of thereference target in the reference image.

When the image capturing apparatus determines that the reference imagefeature is consistent with the temporary image feature, the imagecapturing apparatus may extract the first temporary scale informationand the second temporary scale information of the temporary target fromthe temporary image, wherein the first temporary scale information maybe a width value of the temporary target in the temporary image, and thesecond temporary scale information may be a height value of thetemporary target in the temporary image.

When the value of the first reference scale information is larger thanthe value of the first temporary scale information, the image capturingapparatus may calculate a difference between the first reference scaleinformation and the first temporary scale information, and if theabsolute value of the difference is larger than a preset threshold, theaircraft body may increase its flying speed.

When the value of the first reference scale information is smaller thanthe value of the first temporary scale information, the image capturingapparatus may calculate a difference between the first reference scaleinformation and the first temporary scale information, and if theabsolute value of the difference is larger than a preset threshold, theaircraft body may reduce its flying speed.

When the value of the second reference scale information is larger thanthe value of the second temporary scale information, the image capturingapparatus may calculate a difference between the second reference scaleinformation and the second temporary scale information, and if theabsolute value of the difference is larger than a preset threshold, theaircraft body may increase its flying speed.

When the value of the second reference scale information is smaller thanthe value of the second temporary scale information, the image capturingapparatus may calculate a difference between the second reference scaleinformation and the second temporary scale information, and if theabsolute value of the difference is larger than a preset threshold, theaircraft body may reduce its flying speed.

When a position of the temporary target captured by the image capturingapparatus in the temporary image is located away from the referencepoint, it is necessary to adjust the flying direction of the aircraftbody in time. The position of the temporary target in the temporaryimage may always be kept at the reference point by the adjustment of theflying direction. Therefore the target tracking method suitable for theaircraft may also include the following steps.

When the image capturing apparatus determines that a temporary verticalcoordinate of the temporary position information (i.e., the temporaryordinate of the temporary position information) is not consistent withan initial vertical coordinate of the initial position information(i.e., the initial ordinate of the initial position information), adifference between a temporary vertical coordinate and an initialvertical coordinate may be calculated to generate longitudinaldisplacement information, wherein the initial vertical coordinate may bea position coordinate acquired by the image capturing apparatus in thecoordinate system established based on the reference image, and thetemporary vertical coordinate may be a position coordinate acquired bythe image capturing apparatus in the coordinate system established basedon the temporary image.

The pitch axis of the gimbal may be rotated according to thelongitudinal displacement information to adjust a vertical angle of theimage capturing apparatus for capturing a temporary image.

When a temporary horizontal coordinate of the temporary positioninformation is not consistent with an initial horizontal coordinate ofthe initial position information, a difference between the temporaryhorizontal coordinate and the initial horizontal coordinate may becalculated to generate lateral displacement information, wherein theinitial horizontal coordinate may be a position coordinate acquired bythe image capturing apparatus in the coordinate system established basedon the reference image, the temporary horizontal coordinate may be aposition coordinate acquired by the image capturing apparatus in thecoordinate system established based on the temporary image.

The yaw axis of the gimbal may be rotated according to the lateraldisplacement information to adjust a horizontal angle of the imagecapturing apparatus for capturing a temporary image.

In another implementation, the pitch axis and yaw axis of the gimbal maybe rotated simultaneously so that the temporary vertical coordinate andthe temporary horizontal coordinate may change simultaneously.

Further, in the process of tracking a temporary target by the aircraftbody, the temporary target may be subject to deformation, a color changeor the like due to its own reasons or external reasons. The temporaryimage features of the target including but not limited to gradientdirection histogram, local binary pattern histogram, scale invariantfeature transformation, and accelerated robust feature may change. Inthis case, the present invention employs a method of establishing atarget group and updating a temporary image feature, or the like.

The image capturing apparatus may search for a similar target in realtime in a temporary image and extract a reference feature of a similartarget. When the reference feature is consistent with one of thetemporary image features, for example, the color of the similar targetis the same as the color of the temporary target, or the color and shapeof the similar target are the same as the color and shape of thetemporary target respectively, then the similar target may be regardedas a candidate target in the target group.

When the aircraft body detects a change in any of the temporary imagefeature, the temporary position information, the first temporary scaleinformation, and the second temporary scale information, the temporaryimage feature, the temporary position information, the first temporaryscale information, and the second temporary scale information after thechange may be used to update the temporary image feature, the temporarylocation information, the first temporary scale information, and thesecond temporary scale information before the change respectively, toeliminate or reduce the interference with the tracking system due tofactors such as a target appearance change or occlusion and so on, andthus to improve the stability of the tracking system and the accuracy ofthe tracking results.

In order to facilitate an operator to view, in the present invention,the position information and the scale information of the candidatetarget or the temporary target tracked by the aircraft body may beselectively displayed on the image capturing apparatus (the imagecapturing apparatus may have a display function). In one embodiment, theimage capturing apparatus may be connected to a display, and the displaymay be used to display the position information and the scaleinformation of the candidate target or the temporary target.

The image capturing apparatus may acquire and calculate the provisionalcoordinate information, the first provisional scale information and thesecond provisional scale information of the similar target, wherein thefirst provisional scale information may be a width value of the similartarget in the temporary image, and the second provisional scaleinformation may be a height value of the similar target in the temporaryimage.

When the image capturing apparatus detects a target group and the imagecapturing apparatus tracks a temporary target, the provisionalcoordinate information, the first provisional scale information, and thesecond provisional scale information of the target group may be weightedwith the temporary position information, the first temporary scaleInformation and second temporary scale information of the temporarytarget respectively, and the result of the weighting calculation may beoutput to the image capturing apparatus to display the result of theweighting calculation.

As an example of tracking a vehicle by the aircraft, when there is morethan one vehicle in front of the aircraft and the colors of the vehiclesare the same, the vehicles other than a temporary target may beclassified into a target group. In this case, the provisional coordinateinformation, the first provisional scale information, and the secondprovisional scale information of each vehicle in the target group may beweighted with the temporary position information, the first temporaryscale information and the second temporary scale information of thetemporary target, namely the vehicle to be tracked, respectively, andthe result of the weighting calculation may be output to the imagecapturing apparatus to display the result of the weighting calculation.

When the image capturing apparatus does not detect a target group andthe image capturing apparatus tracks a temporary target, the temporaryposition information, the first temporary scale information, and thesecond temporary scale information of the temporary target may be outputto the image capturing apparatus to display the temporary positioninformation, the first temporary scale information and the secondtemporary scale information.

As an example of tracking a vehicle by the aircraft, when there is onlyone vehicle in front of the aircraft, the vehicle is a temporary target.The temporary position information, the first temporary scaleinformation, and the second temporary scale information of the vehiclemay be output to the image capturing apparatus to display the temporaryposition information, the first temporary scale information, and thesecond temporary scale information.

When the image capturing apparatus detects a target group and the imagecapturing apparatus does not track a temporary target, the provisionalcoordinate information, the first provisional scale information, and thesecond provisional scale information of the target group may be weightedrespectively, and the result of the weighting calculation may be outputto the image capturing apparatus to display the result of the weightingcalculation.

As an example of tracking a vehicle by the aircraft, when there are aplurality of vehicles in front of the aircraft but none of them is atemporary target, and one of the features of the vehicles is the same asthat of the vehicle to be tracked, the plurality of vehicles may beclassified into a target group. In this case, the provisional coordinateinformation, the first provisional scale information, and the secondprovisional scale information of each vehicle in the target group may beweighted respectively, and the result of the weighting calculation maybe output to the image capturing apparatus to display the result of theweighting calculation. When the image capturing apparatus does notdetect a target group and the image capturing apparatus does not track atemporary target, no information will be output to the image capturingapparatus.

The above results output to the image capturing apparatus may also bedisplayed on the display so that an operator can view the details oftracking a target by the aircraft in real time.

For example, the aircraft body may track a bird. The bird to be trackedmay receive a GPS signal. If the aircraft body is initiated, theaircraft body may fly toward a location corresponding to the GPSpositioning signal, and during the flight, the image capturing apparatusmay take pictures of an area where the bird is located to obtain areference image. The image capturing apparatus may extract a referenceimage feature of a reference target from the reference image, forexample, the size and the color of the bird, and the like, and mayextract the initial position information of the reference target in thereference image. It is assumed that the bird is located at the centerpoint of the reference image. The aircraft body may take pictures duringthe flight. When the image capturing apparatus acquires a temporaryimage showing a temporary target, a temporary image feature of thetemporary target and the temporary position information of the temporarytarget in the temporary image may be extracted from the temporary image.When the reference image feature and the temporary image feature areconsistent, the image capturing apparatus may calculate the deviationdirection based on the difference between the initial positioninformation and the temporary position information. The aircraft bodymay track based on the deviation direction. In addition, the imagecapturing apparatus may extract a width value and a height value of thereference target from the reference image. When the image capturingapparatus determines that the reference image feature and the temporaryimage feature are consistent, that is, the temporary target is the birdto be tracked, the image capturing apparatus may extract a width valueand a height value of the bird from the temporary image. When the widthvalue and the height value of the reference target are inconsistent withthe width value and the height value of the bird extracted in thetemporary image, it may show that the distance between the aircraft bodyand the bird may deviate from a preset threshold. For example, if thewidth value of the reference target is greater than the width value ofthe bird extracted from the temporary image, it may show that thedistance between the aircraft body and the bird may be larger than athreshold, therefore the aircraft body may increase its flying speed sothat the distance between the aircraft body and the temporary target maybe kept within a threshold range. The threshold range may be set between0.9*threshold and 1.1*threshold in the present invention. When thetemporary target deviates from the center point of the reference image,the image capturing apparatus may calculate a difference between atemporary vertical coordinate and an initial vertical coordinate andgenerate longitudinal displacement information, and the pitch axis ofthe aircraft body may be rotated according to the longitudinaldisplacement information to adjust a vertical angle of the imagecapturing apparatus for capturing a temporary image. Thereafter, theimage capturing apparatus may calculate a difference between a temporaryhorizontal coordinate and an initial horizontal coordinate and generatelateral displacement information, and the yaw axis of the aircraft bodymay be rotated according to the lateral displacement information toadjust a horizontal angle of the image capturing apparatus for capturinga temporary image. In this way, by adjusting the aircraft body, theflying direction of the aircraft body may direct toward the bird to betracked in real time, while in the temporary image acquired by the imagecapturing apparatus, the bird may be kept at the center point of thereference image, and thus it is convenient for viewing, while avoidinglosing track of the target.

While specific embodiments of the present invention have been describedabove, it should be understood by those skilled in the art that theseare merely illustrative and that various changes or modifications may bemade to these embodiments without departing from the principle andessence of the present invention. Accordingly, the scope of the presentinvention is defined by the appended claims.

What is claimed is:
 1. An obstacle avoidance system of an aircraftcomprising an image capturing apparatus, a gimbal stability-enhancementsystem, and a second controller; the gimbal stability-enhancement systemcomprising a gimbal body and a gimbal control system, the imagecapturing apparatus being arranged on the gimbal body and beingconfigured for capturing an image in a flying direction when theaircraft is flying, the gimbal control system being connected to thegimbal body; the second controller being configured for determiningwhether an obstacle exists in the image captured by the image capturingapparatus, and if yes, changing the flying direction of the aircraftaccording to a position of the obstacle, and if not, controlling theaircraft to fly in the current flying direction, wherein the secondcontroller is further configured for adjusting the flying speed of theaircraft according to a relationship between reference scale informationof a reference target in a reference image and temporary scaleinformation of a temporary target in a temporary image when it isdetermined that an obstacle exists in an image captured by the imagecapturing apparatus; wherein the temporary image is an image, amongimages captured by the image capturing apparatus, where an obstacleexists and whose capture time is closest to the current time; thereference image is an image, among images captured by the imagecapturing apparatus, where an obstacle exists and whose capture time isprior to the capture time of the temporary image; the obstacle in thereference image is referred as a reference target; and the obstacle inthe temporary image is referred as a temporary target, and wherein thesecond controller is further configured for: extracting a referenceimage feature of the reference target from the reference image;extracting a temporary image feature of the temporary target from thetemporary image; extracting the reference scale information of thereference target from the reference image and extracting the temporaryscale information of the temporary target from the temporary image whenit is determined that the reference image feature and the temporaryimage feature are consistent; and calculating a difference between thereference scale information and the temporary scale information when thetemporary scale information is greater than the reference scaleinformation, and reducing the flying speed of the aircraft if theabsolute value of the difference is greater than a difference threshold.2. The obstacle avoidance system of claim 1, wherein the gimbal controlsystem comprises a first controller, a first motor and a second motor,the first motor and the second motor are configured for controlling therotation of the gimbal body in the axial direction of the Pitch axis andthe Roll axis of a three-dimensional coordinate system respectively, thefirst controller comprises a balance control module, the balance controlmodule is electrically connected to the first motor and the second motorrespectively and is configured for controlling operation of the firstmotor and the second motor; the gimbal control system further comprisesa third motor for controlling the rotation of the gimbal body in theaxial direction of the Yaw axis of the three-dimensional coordinatesystem, the balance control module is further electrically connected tothe third motor and is configured for controlling operation of the firstmotor, the second motor and the third motor.
 3. The obstacle avoidancesystem of claim 1, further comprising a distance measurement module;wherein the second controller is further configured for invoking thedistance measurement module to detect a distance between the aircraftand an obstacle when it is determined that the obstacle exists in animage captured by the image capturing apparatus, changing the flyingdirection of the aircraft according to a position of the obstacle if thedistance is less than or equal to a distance threshold, and controllingthe aircraft to fly in the current flying direction if the distance isgreater than the distance threshold.
 4. The obstacle avoidance system ofclaim 1, wherein the second controller is further configured fordetermining whether the altitude of an obstacle is higher than theflying altitude of the aircraft when it is determined that the obstacleexists in an image captured by the image capturing apparatus, and ifyes, increasing the flying altitude of the aircraft, and if not,controlling the aircraft to fly in the current flying direction.
 5. Theobstacle avoidance system of claim 3, wherein the second controller isfurther configured for invoking the distance measurement module todetect a distance between the aircraft and an obstacle when it isdetermined that the obstacle exists in an image captured by the imagecapturing apparatus, and adjusting the flying speed of the aircraftaccording to a relationship between the distance and a preset threshold.6. The obstacle avoidance system of claim 4, wherein the adjusting theflying speed of the aircraft according to a relationship between thedistance and a preset threshold comprises reducing the flying speed ofthe aircraft when the distance is less than or equal to the presetthreshold.
 7. The obstacle avoidance system of claim 1, wherein theobstacle avoidance system comprises a plurality of image capturingapparatuses, which are arranged in different directions of the gimbalbody respectively and are configured for capturing images in differentdirections respectively, wherein the capturing images in differentdirections comprises capturing an image in a flying direction when theaircraft is flying.
 8. The obstacle avoidance system of claim 7, whereinthe obstacle avoidance system comprises three image capturingapparatuses arranged on the gimbal body respectively, and optical axesof lenses of the three image capturing apparatuses are located on thesame plane and the angle between optical axes of lenses of two adjacentimage capturing apparatuses is 120°.
 9. An obstacle avoidance method foran aircraft, the obstacle avoidance method comprising: a step S₁ ofcapturing an image in a flying direction when the aircraft is flying; astep S₂ of determining whether an obstacle exists in the captured image,and if yes, performing a step S₃, and if not, performing a step S₄; thestep S₃ of changing the flying direction of the aircraft according to aposition of the obstacle; and the step S₄ of controlling the aircraft tofly in the current flying direction, wherein the obstacle avoidancemethod further comprises: adjusting the flying speed of the aircraftaccording to a relationship between reference scale information of areference target in a reference image and temporary scale information ofa temporary target in a temporary image when it is determined that theobstacle exists in the captured image in the step S₂; wherein thetemporary image is an image, among the captured images, where anobstacle exists and whose capture time is closest to the current time;the reference image is an image, among the captured images, where anobstacle exists and whose capture time is prior to the capture time ofthe temporary image; the obstacle in the reference image is referred asa reference target; and the obstacle in the temporary image is referredas a temporary target, and wherein the method further comprises:extracting a reference image feature of the reference target from thereference image; extracting a temporary image feature of the temporarytarget from the temporary image; extracting the reference scaleinformation of the reference target from the reference image andextracting the temporary scale information of the temporary target fromthe temporary image when it is determined that the reference imagefeature and the temporary image feature are consistent; and calculatinga difference between the reference scale information and the temporaryscale information when the temporary scale information is greater thanthe reference scale information, and reducing the flying speed of theaircraft if the absolute value of the difference is greater than adifference threshold.
 10. The obstacle avoidance method of claim 9,further comprising: performing a step T₁ when it is determined that anobstacle exists in the captured image in the step S₂; and the step T₁ ofdetecting a distance between the aircraft and the obstacle, andperforming the step S₃ if the distance is less than or equal to adistance threshold, and performing the step S₄ if the distance isgreater than the distance threshold.
 11. The obstacle avoidance methodof claim 9, further comprising performing the step P₁ when it isdetermined that an obstacle exists in the captured image in the step S₂;and the step P₁ of determining whether the altitude of the obstacle ishigher than the flying altitude of the aircraft, and if yes, increasingthe flying altitude of the aircraft, and if not, controlling theaircraft to fly in the current flying direction.
 12. The obstacleavoidance method of claim 9, further comprising: transmitting thecaptured image to a remote controller for controlling the aircraft. 13.The obstacle avoidance method of claim 12, further comprising: receivinga control signal from the remote controller and controlling the aircraftaccording to the control signal.
 14. The obstacle avoidance method ofclaim 10, further comprising: detecting a distance between the aircraftand an obstacle when it is determined that the obstacle exists in thecaptured image in the step S₂, and adjusting the flying speed of theaircraft according to a relationship between the distance and a presetthreshold.
 15. The obstacle avoidance method of claim 14, wherein theadjusting the flying speed of the aircraft according to a relationshipbetween the distance and a preset threshold comprises reducing theflying speed of the aircraft when the distance is less than or equal tothe preset threshold.
 16. The obstacle avoidance method claim 9, whereinthe aircraft comprises a plurality of image capturing apparatuses, whichare arranged in different directions of the gimbal body of the aircraftrespectively and are configured for capturing images in differentdirections respectively, wherein the capturing images in differentdirections comprises capturing an image in a flying direction when theaircraft is flying; wherein the obstacle avoidance method furthercomprises: splicing the images captured by these image capturingapparatuses into a panoramic image.